As a kind of device for projecting digital images and videos, projectors are widely applied in education, business, home entertainment, and other fields and function as playback devices like TV sets. The difference in working features between a projector and a TV set lies in that the projector needs to work with a separate screen to display an image.
The projector projects light beams of an image through a projection lens of an optical system to a screen at a certain distance so as to display the image. The size of an image projection is in direct proportion to the distance between the projection lens and the screen. The horizontal direction, vertical direction, and azimuth angle of the light beams of the image are required to be precisely aligned with the screen; otherwise, the image will have problems such as keystone effect.
Although the projector generally has a keystone correction function to solve this problem, the keystone correction function distorts the image. Therefore, the horizontal direction, vertical direction, and azimuth angle of the projector are required to be precisely aligned with the screen during installation, so as to achieve an optimal image display performance. Therefore, the projector needs to be installed by technicians specializing in this field.
When a projector is used, people usually adopt the following mounting manners: hanging the projector on a wall, directly supporting the projector on a desktop, or suspending the projector from a ceiling.
The manner of hanging the projector on a wall is usually used for short-focus projectors, in which a special wall bracket is used and the projector can be fixed horizontally to project a large image on a screen at a short distance. This manner is usually used in occasions such as interactive education and conferences. The length of a suspension arm of the wall bracket affects the size of an image projection, and usually a sufficiently long suspension arm is used to generate a sufficiently large image. However, due to the leverage effect of the horizontal bracket, an excessive load on the suspension arm leads to a considerably large bending force on the suspension arm. Therefore, a general solution is to use a projector with a shorter focal length or a lighter projector, so as to reduce the length of the suspension arm or the bending force on the suspension arm.
In the manner of supporting the projector on a desktop, the position of the projector needs to be changed frequently. When it is inconvenient to use a bracket to fix the projector, this manner is the simplest. However, to make the projector project an image to a proper height while being precisely aligned with a screen, the projector needs to be placed on a desktop at a proper height, which causes inconvenience.
In the manner of suspending the projector from a ceiling, the projector is fixedly hung upside down from the ceiling by using a special bracket, and the height of an image projection can be correspondingly adjusted by adjusting the length of a suspension arm of the bracket. This manner is adopted by most people, and especially, is widely applied to home entertainment to play large-screen high-definition films. When the projector is for home use, people have preferences for appearance and the space it occupies. It is generally considered that a bracket hung from the ceiling destroys the aesthetics of home furnishing, and therefore, an electric bracket is designed.
The electric bracket can hide the projector in a false ceiling when the projector is not in use, and hang the projector down when it is in use, thereby solving the problems concerning the aesthetics of home furnishing and the space occupied by the projector. However, the electric bracket needs a high-power motor to drive the whole projector lifting system, and therefore has the following problems: a heavy electric bracket, a large occupied space, high costs, a sacrifice of a vertical space in a house, and a need of a false ceiling.
In addition, installation of the electric bracket needs to be completed by professional technicians because it involves specialized techniques and complex procedures. Therefore, considerable labor costs are incurred. Because there is no standard or specification for a connection interface between a bracket and a projector, and parameters such as shape, weight, and mounting hole of different projectors are not necessarily the same, special brackets or brackets suitable for projectors of different shapes and weights are needed. Some projector manufacturers therefore provide special brackets matching their own projectors. Universal brackets suitable for installation of most projectors are also designed, in which special components such as movable irregular hinge elements are attached to the bracket, and many hole sites or wide hole sites are provided in the bracket, so as to cater for different shapes, positions, distances, and numbers of mounting hole sites of projectors.
However, the universal bracket has a lot of movable joints, which become loose easily, and need to be calibrated before being connected to the projector. In addition, adding these accessories sacrifices the overall aesthetics of and increases the space occupied by a projector installation system, adds additional procedures, and also makes the fixation and installation of the projector less firm.
Further, prior to the present patent application, to implement the lifting function into a projector system, a person skilled in the art generally conceives of an additional electric bracket, and considers it to be the most convenient and universal solution.
Since 1968 when the first LCD projector appeared, all text books, technical publications, technicians, and even installation manuals of projector manufacturers use such technical means as the only solution, and it has become conventional and common knowledge. None of the large number of periodicals, patent documents and products for improving the performance and appearance of the electric bracket system of the projector goes beyond this knowledge. Considering the external bracket, which is universal and can fit different projectors, as the most convenient projector installation solution, people exclude possibilities and technical solutions from other aspects.
However, the applicant considers that such knowledge deviates from the objective fact because there is no standard or exemplar for a connection interface between a bracket and a projector, and parameters such as shape, weight, and mounting hole of different projectors are not necessarily the same, and as a result, special brackets are needed. As described in the background, the special brackets have a lot of problems.
The present patent application uses a technical solution different from the prior art, and uses an embedded electric suspension arm to drive a movable optical engine system, which not only achieves the projector raising/lowering function in the prior art, but also brings better effects, and avoids technical problems caused by the non-standard connection between the bracket and the projector.